Classes not Serializable by mistake

Trying to serialize some queries, I found that there are a classes that do not implement Serializable, although there does not seem to be a reason not to. Also, there are classes implementing Serializable which contain fields that are not. Just a few examples:

Classes that have a "serialVersionUID" but do not implement Serializable:org.activiti.engine.impl.variable.BooleanType.classorg.activiti.engine.impl.variable.NullType.class… and almost all the other classes in that package, some not having a "serialVersionUID".All "VariableType"s should implement Serializable, because it is referenced, for example, in the serializable class org.activiti.engine.impl.persistence.entity.HistoricVariableUpdateEntity…

I'd open a JIRA-Issue for this, if no one disagrees that there should be an effort done to remedy this 'situation'.